This invention relates to an improved method and apparatus for metering electricity at multiple rates depending upon the time of day and time of week during which consumption of electricity is being measured.
In electrical distribution systems, electrical energy has heretofore been sold quite generally on the basis of a fixed rate schedule irrespective of whether a high or low demand has been made upon the electrical generation system. Because of this, the electrical generation and distribution system has been found to be, at times, overloaded and, at other times, to be only very slightly loaded. This results in substantial inefficiencies since a much larger plant and distribution system than is economically desirable is required in order to meet peak demands of the distribution system.
In order to provide for more efficient use of electrical generation and distribution facilities during off-peak load periods, attempts have been made at developing clock mechanisms for decreasing the flow of electricity during peak load periods. Generally, in the past, these types of devices have been found to be impractical due to the necessity of frequent checking and setting of the clock switching mechanisms at the various consumers locations and, in addition, to the inability to predict peak demand load intervals and to change the timing of the clock mechanisms on a relatively simple and efficient basis to track the peak load intervals.
Very early in the supply of electricity over a relatively large distribution areas, attempts were made at multiple rate metering of electrical power consumption. As an example of a prior attempt to individually register different amounts of power consumed during different intervals of a day, Greenwood et al disclosed in U.S. Pat. No. 2,139,821 a simplified arrangement wherein a two-stage mechanical watt meter mechanism was provided having a clock timer associated therewith. Cams on the clock timer tripped a mechanism which, at selected times during the day, permitted the driving of one set of meter dials or the other so that consumption of electrical energy, during a selected portion of the day, could be registered by only one set of dials, while the electrical energy consumed during the other portion of the day could be registered on a second set of dials. This arrangement was followed by the developments of Pratt, as disclosed in U.S. Pat. No. 2,246,185 and Cameron, as disclosed in U.S. Pat. No. 2,132,256. The Pratt and Cameron developments both utilized dual rate metering systems wherein a clock determined which set of meters were to be activated. Other attempts have been made at providing a dual rate kilowatt hour metering system, as exemplified by the following patents: Barstow U.S. Pat. No. 548,419; Cox U.S. Pat. No. 585,258; Oxley U.S. Pat. No. 591,195; Oxley U.S. Pat. No. 593,852; Wilson U.S. Pat. No. 596,283; Kapp U.S. Pat. No. 597,985; Oxley U.S. Pat. No. 710,070; Mayer U.S. Pat. No. 1,078,206; Ogurkowski U.S. Pat. No. 2,415,653; and Kahn U.S. Pat. No. 2,915,704.
In addition to the aforementioned two-rate mechanical registering systems, other systems have been developed wherein the use of power above a certain level is recorded. This excess consumption does not relate to time-of-day metering, but rather is a proposed means of reducing the peak use of power by a particular customer. Such systems minimize individual peak power usage which may or may not coincide with the peak power demand on a utility system. It is a purpose of the present invention to provide a system for individually measuring the consumption of power from an electrical generation and distribution system during the peak demand intervals of the system in order to encourage consumers of electrical power to shift consumption of power to off-peak intervals.
In view of the aforementioned, it is an object of this invention to provide an improved method and apparatus for measuring and displaying electrical power consumption on different meter displays depending upon the time of day and time of week during which the power is being consumed.